Electrically driven percussion drill, particularly for drilling rock, earth, and synthetic substances



June 28, 1960 D. MU'rHMANN 2,942,852

ELECTRICALLY nRIvEN PERCUSSION DRILL. PARTICULARLY FOR DRILLING Rocx. EARTH AND SYNTHETIC suBsTANcEs Filed Jan. 24, 1957 Fg@ f5 195'# f4 17 a UnitedStates Patent 2,942,852 Patented June 28, 1960 ELECTRICALLY DRIVEN PERCUSSION DRILL, PARTICUIARLY FOR DRILLING ROCK, EARTH, AND SYNTHETIC sUnsTANcEs Dieter Muthmami, onkel-Tom-strasssiss,

Berlin-Zehlendorf, Germany t Filed Jan. 24, 1957, Ser. No. 636,099

3 Claims. Y (Cl. 255-4'3) In the construction industry, percussion drills are needed, for example in order to be able to drill through walls, masonry, door-posts etc. in the shortest possible time to lay gas, water and electric conduits. `Such ma- 'chines work with a drill spindle to which axial percussion movements are imparted during the drilling operation. lThese percussion movements may be produced by two -discs which are axially toothed or provided with cam- Vlike surfaces, and one of which remains stationary while `the other rotates with the drill spindle. If the two opposed discs with tooth-like or cam-like projections are subjected to a spring pressure or the pressure Yexerted Von the -drill by the operator, y,which urges the discs together, then l.the axially displaceable toothed or cam disc, which is rigidly connectedto the drill spindle, performs percussionlike movements, the frequency of which depends'on the number of teeth'or cam-surfaces slidngover one another .and on the-speed imparted to the drill spindle.

It is the object of the invention to develop percussion drills of thetype described above in the sense ofv a con- :structional simplication and by providing a device for regulating the percussion amplitude which can be adjusted `easily while the percussion drill is in service.

According to the invention, this problem is solved by the fact that the distance between the teeth on the rotating notched discrand the teeth on the stationary noched disc, through the middleof which` projects the pin for the drill spindle, 'can be varied by means of a percussionadjusting nut which is mounted coaxial with the drill spindle, and between the end of which'facing the drill chuck and a collar on" the drill' spindle there fis mounted a thrust .bearing which takes up thethrust of the percussion drill. The thrust bearing is rigidlj/connected to the percussion adjusting nutY and by turning the latter, the former is adjustable in its axial position in rellation to the stationary notched disc at various main stops, Aeach of which is iixed by a resilient detent pin, in such aA manner that at the stop theY teethof the tW'o notched ldiscs do not touch one another, at another stop the teeth .are fully engaged and at'the remaining stops contact be- 'tween the teeth takes place to a varying degree in eachV CaSe.

notched discs and coaxial therewith is a cylindrical hollow body and xed to its inner diameter is a liner for the drill spindle. The end of this hollow body which projects from the aforesaid honsing'por'tio'n is provided externally with a thread, for screwing on the percussion adjusting nut. Mounted for longitudinal displacement in a bore in the wall of the cylindrical hollow body and parallel to the axis thereof, is a detent pin which is subject to the pressure of a spring and which engages in depressions in the percussion adjusting nut. In this manner, assurance is provided that the engaged position of the percussion adjusting nut remains unaltered by the vibrations of the percussion drill operation, until the operator of the percussion drill has changed the percussion amplitude setting to another stop.

The various stop positions are preferably indicated by gures on the outer periphery of the percussion adjusting nut so that it is possible to see which stage of the percussion amplitude the drill spindle is performing in operation. if the mark is opposite the iigure 0, this means that the teeth of the notched discs are not in engagement with one another, that is to say that no percussion movements are being imparted to the drill spindle.

One embodiment is illustrated by way of example in the accompanying drawings, wherein:

Fig. 1 is an elevational view of a percussion mechanism of the invention with a portable drill attached;

Fig. 2 is a large scale elevational view partly in section, of the percussion mechanism;

Fig. 3 is an elevational view, partly in'section, of the drill spindle and driving pin and a notched disc secured to the drill spindle; and

Fig. 4 is an end view thereof.

Figure l shows that the percussion drill consists of a motor portion 1, a housing portion 2, surrounding cam and cam follower means such as the notched discs 7 and S (Fig. 2), the percussion adjusting nut 3, the drill spindle 4 and the drill chuck 5. Only the mechanism which im- 'v will be described below.`

Screwed into the housing portion surrounding the two Y Fixed in the end of the percussion adjusting nut 3 facing the drill chuck S is a thrust bearing 6 which takes up the percussion drill thrust. `The notched disc 7 is rigidly connected to the drill spindle 4 by means of a pin 17. The teeth 7 of the notched disc 7- have the'same prole as the teeth 8 of the notched disc 8 which is rigidly connected to the housing 2 by means of the grub screw 9. The driving pin 10 for the drill spindle 4 is integral therewith, as best shown in Fig. 3, and isattened on two opposite sides as shown in Fig. 4 and projects through a bore in the notched disc 8. VThis driving pin 10 is coupled in known manner with the shaft which projects from the motor portion 1 and which is not illustrated in Figures 1 and 2. v

Screwed into the housing portion 2- is a cylindrical hollow body 11 to the inner diameter of which is lxed a liner l2 for the drill spindle 4. The end of the hollow body 11 which projects from the housing portion2 is provided with a thread 3 on which the percussion adjusting nut 3 is screwed. Mounted for longitudinal displacement in a bore 19, theraxis of which runs parallel to the axis of the hollow body 11, is a detent pin 13 which is urged by the pressure of a spring 14 into a depression 15 sions 15 are arranged in a circle round the inner end of the percussion adjusting nut 3. Each of these depressions corresponds to astop position of the percussion adjusting'nut 3. Since in the example illustrated in Figures 1 and 2 there are four stop positions for the percussion adjustingV nut 3, namely the stops 0, '1,2 and 3, there must oe four depressions 1S present altogether, in which the same detent pin i3 engages one after the other. 4

The percussion drill spindle 4 is provided with a collar 16 against which, during operation ofthe percussion drill, rests the thrust bearing 6 which is located in the end of the percussion adjusting nut 3 facing the drill chuck 5.

in Figure 2, the reference numeral 18 represents a hall oiler by means of which the flanks of the teeth 7' Y and 8 of the notched discs 7 and 8, which slide over one The machine therefore operates as a drilling Y machine without any percussion movement of the drill y spindle. If the percussion adjusting nut 3 is in the stop position 3, however, then the oblique flanks of the teeth 7 and 8 rest on one another. With the shape of the teeth illustrated, the .notched disc 7 would be driven in clockwisewdirection. Onrotation of the spindlei, itjs teeth v7"run on the oblique vll'annlcs ot the teeth 8 of the notched disc 8 which is stationary in the Vhousing V2 and'repeatedly engage iin the gaps between the teeth `8 under theV influence'of the pressure exerted on the driil spindle 4 by the operator. In this manner, percussion movements are imparted to the drill spindle 4.

When the apparatus is'applied lby an operator toa wall surface, the drillv spindle 4 Vwill be axially stationaryexcept forpenetration into the wall as the drilling y,preg'ress'es During rotation of the dril1"spindle"4,'the cam action betweenY the discsl and Swill interriiittent'lypush the ldisc: 8 and therewith the` housing Z outwardly away fromthe wall and towards theopera'tor, and release the dise 8 yand the housing 2 during the intervals between the outward thrusts. `T he operator will continue throughout to exert pressure onto the housing `2, so 'that during j these intervals the discs Tand `8 will be interengaged and the bearing 6 make impact with the collar 16 of fthe d'rilhspindle.

' "When-the 'percussion adjustingv nut 3 is in the stop position 2, the flanks of the 'teeth V7' and 8 Yarea somewhat apartfrorn one another. This spacing apart is Vfurtheriinc'reasedfin `the Ystop position `1. In both stop positions', however, theteeth still slide overone another and t Yimpart percussion movements of a` smaller amplitude in comparison with stop position Yil,V to the spindleV '4.

`VZWheu the percussion adjusting nut V3 is turned in suchVV amanner'thatit moves on the threading' of the 'hollow body `11 screwed into the housing '2, towards the motorV portionVV 1, then itr'takes the thrust bearing 6 VwithV it because the latter is rigidly connected to thepercussion adjusting'nut. V'I'h'e collar "16 of the percussion drill spindle `4 always rests against the thrust bearing 6 whentthe 'drillis in operation, becaseiof thel pressure exerted on the spindle'4 by the operator, so ythat'the' distance betweenjthe teeth 7 and '8' of the notched discs `7Y and t8 which has beenset by the percussion adjusting nut 3 cannotbe affected by this'pressure; i The percussion frequency is normally varied by vary ing'th'e speed of the drivingmotor of the percussion drill.

said-housing foraxial relative'movement; between said saidlectric mtorfandtoca'rry atV its forward endV a drill,

Y afrevoluble disc disposed inside said Vhousing and securedV tosaidlspindl'e forrrotation therewith, a stationary disc secured inf'said drill'housingadjacentand coaxial with t i ing mounted on said nut and movable therewith axially of the spindle, and a thrust Ycollar secured to said spindle and disposed adjacent the exterior of said thrust bearitng,v

whereby the threadingrmovement ofthe nut relative to the housing will adjustably position the thrust bearing relative to thrust collar'on the spindle, Vand the force exerted by theoperator against the housing will cause abutment between the thrust bearing and the thrust collar of the spindle as the drill of the spindle `rests on the material to be drilledthu s varying the distance the housing can move relative to the spindle before the b'e'aring contacts the thrust collar. Y

.2- A percussion dan mechanism, for use with an electric motor for the .of material, comprising a housing, a drill spindle journalled for rotation and guided in vsaid housing for axial relative movement .between vsaid spindle and said housingV and-adapted tolbe driven by said Y electric motor and adapted to carry near its forward end a drill, cam and cam follower Ameans rbetween said spindle and said housing disposed on the interior of said housing and operable `upon inter-engagement to cause repeated axial rearward thrusts `ofsaidrhousing when said "spindle revolves, for subsequent forwar'cl'f thrust movement of -the v`lio'lrrsingpunder[manual force applied to the housing byv an operator*- inthe 'intervals between .the rearward thrusts, and m'eansfor `varyingYthe] distance bietween said cam andfc'am followerm'eans comprising a Y nut supported Vin threaded Vengagement l,by said Vhousing and surrounding coaxiallysaid'spindle andheingmov Vable axially Vof said spindle when turned Vrelative to Ysaid housing in threading engagement, a thrust bearing mounted on said nut and beingimovable'ther'ewith Yof said spindle, and a'collarasecuredlto-the lforwardtend of said drill spindle near the forward exterior of said thrust bearing, whereby the threading' movement ofthe nut relative to the housing will adjustably Vposition the Y Ythrust bearing relative tothe thrust'collar on the spindle,

saidrevoluble disc, teeth arranged-around the periphery L' of eachof said discs ancl'including oblique surfaces, the teeth of each disc'being opposite to andV facing those of theother andthe oblique surfaces ofthe teethiof the Y r'evoluble Vdisc being operable totslide on'those of the teeth ofthe stationary disc'to impart during operationito the housing an axial rearward thrust movement when the spindle VVrotates, for subsequent forward'thrusttrnovement ofthe housing under manual forceapplied to the housing and the force exerted bythe operator against the housing will cause abutment between the Ythrust bearing and the thrust Vcollar of the spindleY as .the drill of the spindle rests on the Vmaterial to he drilled, thusvarying the distance thehousing can move relative to theispindlebefore the bearing contacts the thrust. collar.Y l 5 Y3. In a percussion drill mechanism, as claimed in claim 2, together with means ,for releasably locking said nutrelative tojsaid'housing in'various positions comprising a spring-biaseddetent pinrmountedinrthe housing relative to which Vthe nutis movable, said nuthaving a's'eries of notches eachV adaptedfto' beengagedbysaid pin for latchinglof the nut'. i i

fnefftrgnes cited in theme of this patent UNITED STATES PATENTS 888,455 Atkiss et al. Mayr26', 1908 Y2,458,929 Clark Ian. l1, Y1949 2,630,723 Gridley ...i Mai'.V 10, 1954 2,724,573 Lundquist `Nov. v22', ,'1955 2,794,621 

